Process for producing naphthenic lubricating oils



United States Patent O 8 Claims. (Cl. link-36) Our invention relates tothe production of naphthenic type of lubricating oils. Moreparticularly, our invention relates to the production of -naththenictype lubricating oils from lubricating oil distillatefractions derivedfrom Mid-Continent ormixed base crud es Certain crude oils containarelativelyhigh ratio of naphthenic (cycloalkane) compounds comparedwith paraffin compounds. Upon proper refining these crude oils yieldnaphthenic lubricating oils which are 'particu larly desirable "for usein grease, diesel engine lubricants and cutting oil formulations. Thefactors contributing to the particular desirability of naphtheniclubricating oils are their-high grease yields, i.e., a high ratio of oilto soap for a given consistency. -Further, naphtheniclubricating oilsyield soft carbon deposits in diesel engines, particularly in railroaddiesels, and consequently cause less wear on moving parts. Naththeniclubricating oils are highly compatible with the various additives usedin cutting oil compositions and for thisreason are preferred for suchservice. cc c v Due to the specific properties possessed by 'naphtheniclubricating oils the demand 'for them is very great. A Crude oils whichyield such lubricating oils, however, are diminishing in supply and fromtime to time definite shortages of these lubricating oils exist. "On theother hand Mid-Continent or mixed base lubricating oil stocks continueto be in large supply. We have discovered a process whereby thesedesirable naphthenic type lubricating oils can be derived from the moreplentiful Mid-Continent or mixed base lubricating oil stocks.

The pi'ocess of our invention comprises subjecting a mixed baselubricating oil distillate fraction to .solvent extraction by a solventselective for aromatics in a manner to yield a particular.fraction,.dewaxing this particular fraction and hydrogenating thedewaxed fraction. Alternatively, the dewaxing stepcan precede thesolvent extraction. The particular fraction is derived by. particulartreatment of the extract phase of a conventional solvent extraction,rather. than from the normally desirable rafiinate phase. Such extractphases have few known uses and are unsuitable for use as lubricatingoils. Thus, our invention also provides a process for obtainingnaphthenic type lubricating oils from a normally undesirable extractphase.

It is desirable toaobtain a particular fraction from which mostparaifinic and most aromatic components have been excluded, Thisfraction is obtained by separating the. extract phase,.from theconventional solvent extraction of a mixed base lubricating oildistillate fraction, into a second extract phase which is similar to thefirst extract phase in that it has a high aromatic and low paraflincontent and a second raffinate phase from which most of the paraflinsand aromatics have been excluded. It is this second r affinate orheart-cut fraction which is treated 'byihydrogenation in accordance withthe process of our invention. The separation can be carried out bycooling the first extract phase, or by injectingan anti-solvent into theLfirst extractrphase-orfbya combination of cooling andinjectiontofananti-solvent to produce a second extract and rafiinate phase which canthen be separated in a settler with the upper (rafiinate) phase beingthe desired or heart-cutflfraction. The vseparation can alsobe carriedout by subjecting the first extract. phase to re-extraction by means of.a conventional system with a .solvent selective for aromatics, using, alower temperature or by adding a solvent containing an anti-solvent 05using a combination of a lower temperature and the anti-solvent, toproduce the desired railinate or heart-cut fraction, M y y Thus,according to the .process. of. our invention a mixed baselubricating oildistillate fraction is-subjected toa conventionalsolventextraction-process to produce an extract phase. The amount of solventcan vary from to IOOO volume percent solvent based upon the lubricatingoil fraction. The temperature employed in this extraction process canvary somewhat according-to the particular solvent used,-e.g.,phen0l-155to2l0 R; furfural-lSO to 250 Fgliqu-id sulfur dioxide-lessthan 150 F. When it is desired. toseparate this extracttphase intosecond extractand, raflinate phases. using the. cooling or antisolventmethod described above it is not necessary to remove the solvent priorto further processing of the first extract. Inasmuch as the extractremoved from a conventional solvent extraction process will usually beat a temperature about 180 F., it is necessary only to cool the extractto a temperature of about 100 to F. to

' effect phase separation. While phasetse paration can be accomplishedby the injection of a sufficient quantity of anti-solvent, it isdesirable tolimit theinjection of an antisolven-nsuch as water to about5 to 25 percent by volume. When employing water in this quantity it ispreferred to cool the extract to a temperature in the range from about105 to To obtain the second extract andraffinatephases using there-extraction method described above the quantity of solvent employedinthe second extraction step is usually somewhat less than in the firstextraction step. Normally itis satisfactory to employ from '50 to 700volume percent solvent based upon the first extract. As described above,the temperature employed in the reextraction is usually lower thanemployed in the first extraction, e.g., phen'ol90 to F.;fu1ifural-9O to200 F. A more specific description of the methods employed in. this're-extra'ction s'tep of our process can be found in US. Patent No.2,943,990. r

The extraction steps are operated so that the first extract preferablyrepresents from about 20 to about 70 volumepercent of the rawlubricating oil distillate and the second raffinate (the heart-cut)preferably "represents from about 20 to .70 volume percent of the firstextract. In conducting the extraction steps of the process suitablesolvents that can be employed include phenol, furfural, liquid sulfurdioxide, nitrobenzene, 'nitro paraflins and other solvents selectivef0r-aromatics. Such processes and solvents are well known. For example,when employing phenol, a particularly advantageous solvent, the

, extraction comprises passing a feed stock through a phen01 treatingtower, removing a raffinate oil from the top of the tower and removingan extract oil from the bottom and removing the phenol from theraffinate oil and extract oil by distillation. A suitable anti-solventfor use in our process is water.

The dewaxing step of the process of our invention can be carried out byemploying a conventional lubricating oil dewaxing process such assolvent dewaxing, e.g., with a methyl ethyl ketone and toluene solventblend, or urea dewaxing through the formation of adducts of urea andstraight chain parafiins. The dewaxing can precede the solventextraction but for the proper control of pour point it is preferred toextract first and then dewax. The extracted and dewaxed fraction is thensubjected to catalytic hydrogenation.

The hydrogenation step of our process is conducted at a pressure fromabout 1000 to about 3500 p.s.i.g., a temperature from about 600 to about750 F. and at a weight hourly space velocity from about 0.25 to about3.0 pounds of oil per pound of catalyst per hour. Any of the well knownhydrogenation catalysts such as molybdenum, chromium, tungsten,vanadium, platinum, zinc, tin, nickel, copper, iron and cobalt or theiroxides or sulfides either unsupported or supported on a suitablecatalyst carrier such as alumina or silica can be employed in this stepof our process. Particularly advantageous catalysts are the irontransition metals (iron, cobalt and nickel) and the Group VI B metals(chromium, molybdenum and tungsten) especially combinations of metalsfrom each of these groups, for instance, cobalt and molybdenum, nickeland tungsten, and nickel and molybdenum supported on alumina. Of thesecatalysts we prefer to employ a cobaltmolybdate on alumina catalyst suchas that described in US. Patent No. 2,898,308.

If it is so desired, the hydrogenated product of our process can befractionated in order to yield certain narrower fractions particularlysuited to certain end uses.

In our process, specific dispersion can be used to control the varioussteps. Specific dispersion is defined as where W=I6ffflCfiVB index andd=density. Thus, the first solvent extraction preferably should yield anextract having a minimum specific dispersion of 160 and the heartcutfraction preferably should have a specific dispersion between 135 and185. Furthermore, the heart-cut fraction should have a gravity of aboutto 30 API and a viscosity of about 35 to 200 SUS at 210 F. In thehydrogenation step, the specific dispersion of the heart-cut feed shouldbe reduced about 10 to 70, preferably about to 30. Thus, the finalhydrogenated product should have a specific dispersion between 105 and140 depending upon the properties required for end use.

The mixed base lubricating oil distillate fraction is derived from mixedbase crude oils which have a composition intermediate that of theparaffinic, e.g., Pennsylvania, and naphthenic types of crude oil.Generally, mixed base crude oil is found in the Mid-Continent area. Forexample, such crudes include Oklahoma City and East Texas. Inasmuch asthe composition of mixed base crude oils is intermediate that ofparaflinic and naphthenic crudes the physical properties of a mixed basecrude are usually intermediate those of paraflinic and naphtheniccrudes. Thus, the fraction of a mixed base crude boiling between 428 F.and 527 F. at atmospheric pressure will have an API gravity betweenabout 33 and 40 API while the fraction boiling between 527 F. and 572 F.at 40 mm. will have an API gravity between about 20 and API and a cloudpoint above 50 F. The characterization factor of mixed base oilsnormally falls in the range from 11.5 to 12.1. Mixed base crude oils canbe chemically classified as parafiinic-naphthenic crude oils accordingto the system set forth in The Science of Petroleum, volume V, part I,pages 75-77, Oxford University Press, New York, 1953, and A. N.Sachanen, The Chemical Constituents of Petroleum, pages 4l9427, ReinholdPublishing Corporation, New York, 1945. Representative of such crudeoils are an Oklahoma City crude with the approximate composition, byweight, of 36% paraffins, 45% naphthenes, 14% aromatics and 5% resinsand asphaltenes and a ring analysis showing 65% paratfin side chains,25% naphthenic rings and 10% aromatic rings and an East Texas crude withthe approximate composition of 33% paraflins, 41% naphthenes, 17%aromatics and 9% resins and asphaltenes and a ring analysis showing 60%paraffin side chains, 26% naphthenic rings and 14% aromatic rings.Usually Mid-Continent mixed base crude oils will contain from 60 to 70percent by weight parafilnic side chains and at least 20 percent byweight naphthenic rings.

To illustrate further the process of our invention reference is made tothe following example.

Example A mixed base East Texas crude oil was fractionated byatmospheric and vacuum distillation to yield gas, gasoline, kerosene,lube distillate, gas oil and asphalt fractions. The lube distillatefraction had the analysis shown in Table I. This lube distillate wassolvent extracted with phenol on a counter-current extraction towerusing a solvent dosage of volume percent, a top tower temperature of 191F., a bottom tower temperature of 178 F., and 3.2 volume percent ofwater based on solvent injected at the tower bottom. This produced 65.9volume percent yield of rafiinate (Ratfinate A) and 34.1 volume percentof extract (Extract B).

Raffinate A was dewaxed using a 50/50 blend of MEK and toluene and afilter temperature of -10 F. to obtain 68.4 volume percent of dewaxedMid-Continent lubricating oil (Lube C).

Extract B tested 17.3 API gravity, 43.6 SSU at 210 F. viscosity, +60 F.pour, and 194.5 specific dispersion. In order to compare compositions, aportion of Extract B was dewaxed in a manner similar to Rafiinate A toyield 93.0 volume percent of a finished aromatic oil (Lube D).

A second portion of Extract B was batch solvent extracted with phenolcontaining 20.0 volume percent water using a solvent dosage of 665volume percent and a temperature of 105 F. This produced 64.3 volumepercent of raffinate (Raffinate E) and 35.7 volume percent of extract(Extract F). Raflinate E was dewaxed in the same manner as Ratlinate Ato yield 90.2 volume percent of dewaxed lubricating oil (Lube G).

Lube G was hydrogenated at 1500 p.s.i.g., 700 F., and 1.0 WHSV over acobalt-molybdenum supported on alumina, catalyst to yield 98.4 volumepercent of finished naphthenic type lubricating oil (Lube H). Lube Hrepresents the product from the process of this invention.

Two lubricating oil stocks were prepared by the conventional manner froma blend of equal parts of Gulf Coast Pickett Ridge, Damon and Thompsoncrude oils. The crude was fractionated by atmospheric and vacuumdistillation to yield gas, gasoline, light and medium lubrieating oildistillates, gas oil and asphalt. Distillation was over caustic toremove naphthenic acids. The lube distillates were treated with 14 and25 pounds per barrel of 98% sulfuric acid, respectively, neutralizedwith caustic and contacted at 180 F. with 3 pounds of fullers earth perbarrel of oil. Overall yield from the light lubricating oil distillate(Lube J) was 87.3 volume percent and from the medium lubricating oildistillate (Lube K) 83.5 volume percent. These two lubricating oils aretypical of those produced from naphthenic base crude oils.

1 Combination of silica gel chromatography and mass spectrometry.

Table I lists the properties of the various lubricating oils produced inthis example. In obtaining the chromatographic data the procedureemployed is described in the article, Properties of High-BoilingPetroleum Products, L. T. Eby, Analytical Chemistry, vol. 25, page 1057,July 1953. The mass spectrometer methods employed are described in Massspectrometric Analysis of High Molecular Weight Saturated Hydrocarbons,R. J. Clerc, Archie Hood and M. J. ONeal, Jr., Analytical Chemistry,vol. 27, page 868, June 1955, and Composition of an East Texas Lube OilDistillate, B. A. Drkin, J. G. Bendoraitis, R. Brown and R. H. Williams,Symposium on Composition of Petroleum Oils, Determination andEvaluation, sponsored by Research Division IV of ASTM Committee D-2,February 8, 9, 1957, New Orleans.

It will be noted that Lube C, which is a typical Mid- Continent solventrefined oil, difiers considerably in composition from Lubes J and K,typical naphthenic lubricating oils from South Texas Gulf Coast crudeoils. Specifically, Lube C has a considerably higher saturates contentand is particularly rich in paraflin.

Lube D, the aromatic extract, on the other hand is high in aromatics andextremely low in cycloalkanes as compared with Lubes J and K.

Lube G, the heart-cut fraction, is more related to Lubes J and K but isstill high in aromatic content and low in cycloalkanes.

Lube H, hydrogenated Lube G, represents the product of the process ofour invention. It will be noted that Lube H closely approximates thecomposition of Lubes J and K and has similar properties, with theexception of pour point. However, dewaxing conditions for Lube H can beadjusted, for example by reducing the filtering temperature to F., toyield an oil having pour properties more related to Lubes J and K. Moresevere dewaxing will also reduce the paraffin content of Lube H. Thus,it can be seen that the process of our invention produces a lubricatingoil having a composition and properties similar to those of typicalnaphthenic lubricating oils and is obtained by the treatment of a mixedbase lubricating oil fraction.

TABLE I Des at on Lube C Lube D Lube G .LubeH Lube I Lube K IdentityDeWaxedBafi.

Typical Dewaxed Ext. from Solv. Prod. 01 Inv.- Typical N aph: TypicalNaph. RawLube M-Gont. from Solvent .RqfgLube NapbOil De-v sLube. derived;Lube derived Dist. 1 Solv. Rc- Refined Oil Ext. (Lube 1) rived from from Naph- H Irom Naph- Fract. fined Oil (Aromatic Typu Feed to M-C-crude*thenieGrude thenieCrude oil) Hydrogen. Step Laboratory Tests:

Gravity, API 30.1 .33. 0 15.7 21. 0 23.2 22. 5

Vis. esp/ J3- 105. 6 308.8 208, s 150. 0 324,3

Vis. SSU/210" F 38.1 39. 9 A5; 4 43:7 41:1 48. 2

Specific Dispersion l. 135. 0 104. 5 201. 6 158. 5 129. 6 129. 9

Hydrocarbon-Type Analysis, Weight Per- Ipent l z Satin-ates: 1 t

' Parafiins 21. 3 5. 2 9. 7 7. 7 4.0. 3. 9 N oil-Condensed Cycloalkanes42. 8 14. 2 21. 8 28. 2 32:8: 29.6 Condensed Oycloalkanes; 22. 3 9. 816. 6 22. 6 24. 2 27. 5

Aromatics Benzenes 4. 5 9.6 13.0 9.6 8:8 8.1 Indanes, Tetralins. 3.3 12.6 9. 5 10. 4 9. 1 9. 1 Naphthalenes 2. 5 (i. 6 5. 6 5. 1 5. 0 5. 2Diphenyls, Acenaphthalenes 0. 6 8. 9 4. 9 4. 3 4. 7 4. 2 Phenanthrencs,Anthracenes 0. 3 9. 5 3. 8 3. 1 2.9 2. 9 Pyrenes, Fluoranthenes- 0. 6 7.6 3.0 2.0 1. 6 1. 9 Chrysenes 0.6 3. 8 1. 9 1. 7 1. 6 1. 9 Pery1enes 0.58. 2 4. 5 3. 3 2. 9 3. 5

Polar Compounds 0.7 4. 0 5. 1 2. 0 1. 8 2. 2 Total 100. 0 100. 0 100. 0100. 0 100. 0 100. 0

We claim:

1. A process for producing naphthenic type lubricating oils having aspecific dispersion between about and about from a mixed baselubricating oil distillate fraction which comprises subjecting the mixedbase distillate fraction to a solvent extraction treatment including thesteps of extracting the distillate fraction with a solvent selective foraromatics to yield a first extract phase comprising about 20 to about 70volume percent of the mixed base distillate fraction and having aspecific dispersion of at least about and separating the first extractphase into a second extract phase and a second raffinate phase fromwhich second raifinate phase most paraffinic and most aromaticcomponents have been excluded by said solvent extraction treatment andsaid separating and having a specific dispersion of from about 135 toabout and comprising about 20 to about 70 volume percent of the firstextract phase, subjecting said second raffinate phase -to a dewaxingtreatment, and hydrogenating the dewaxed second rafiinate phase while incontact with a hydrogenation catalyst at a temperature from about 600 F.to about 750 F., a pressure from about 1000 to about 3500 p.s.i.g. andat a weight hourly space velocity from about 0.25 to about 3.0 pounds ofthe dewaxed second raffinate per pound of catalyst per hour.

2. The process of claim 1 in which the separation of the first extractphase into the second extract and raffinate phases is accomplished bysubjecting the first extract phase to at least one of the steps ofcooling and injection of an anti-solvent.

3. The process of claim 1 in which the separation of the first extractphase into the second extract and ratfinate phases is accomplished bysubjecting the first extract phase to re-extraction with a solventselective for aromatics including at least one of the steps of coolingand injection of an anti-solvent during the re-extraction.

4. A process for producing naphthenic type lubricating oils having aspecific dispersion between about 105 and about 140 from a mixed baselubricating oil distillate fraction which comprises solvent extractingthe mixed base distillate fraction with a solvent selective foraromatics to yield a first extract phase comprising about 20 to about 70volume percent of said mixed base distillate fraction and having aspecific dispersion of at least about 160,'subjecting the first extractphase to re-extraction with a solvent selective for aromatics andcontaining an antisolvent at a temperature lower than that at which thefirst solvent extraction is conducted to yield a second rafiinate phasefrom which most paraffinic and most aromatic components have beenexcluded by said solvent extraction treatment and said separating andhaving a specific dispersion of from about 135 to about 185, a gravityfrom about 15 to about 30 API and a viscosity from about 35 to about 200SUS at 210 F. and comprising about 20 to about 70 volume percent of saidfirst extract phase, dewaxing the second raifinate phase andhydrogenating the dewaxed second raffinate phase while in contact with ahydrogenation catalyst at a temperature from about 600 F. to about 750F., a pressure from about 1000 to about 3500 p.s.i.g. and at a Weighthourly space velocity from about 0.25 to about 3.0 pounds of the dewaxedralfinate per pound of catalyst per hour.

5. The process of claim 4 in which the hydrogenation catalyst consistsessentially of an iron transition metal and a group VI B metal supportedon alumina.

6. The process of claim 4 in which the hydrogenation catalyst is acobalt-molybdate supported on alumina catalyst.

'7. The process of claim 1 in which the hydrogenation catalyst consistsessentially of an iron transition metal and a group VI B metal supportedon alumina.

8. The process of claim 7 in which the hydrogenation catalyst consistessentially of a cobalt-molybdate supported on alumina.

References Cited by the Examiner UNITED STATES PATENTS 2,248,373 7/1946Merrill et al 20836 2,780,581 2/1957 Macke et a1. 20836 2,943,990 7/1960Rausch et al 20836 2,967,144 1/1961 Cole 20887 2,967,147 1/1961 Cole20887 2,984,616 5/1961 Burke et .al 208-87 DELBERT E. GANTZ, PrimaryExaminer.

ALPI-IONSO D. SULLIVAN, Examiner.

1. A PROCESS FOR PRODUCING NAPHTHENIC TYPE LUBRICATING OILS HAVING ASPECIFIC DISPERSION BETWEEN ABOUT 10K AND ABOUT 140 FROM A MIXED BASELUBRICATING OIL DISTILLATE FRACTION WHICH COMPRISES SUBJECTING THE MIXEDBASE DISTILLATE FRACTION TO A SOLVENT EXTRACTION TREATMENT INCLUDING THESTEPS OF EXTRACTING THE DISTILLATE FRACTION WITH A SOLVENT SELECTIVE FORAROMATICS TO YIELD A FIRST EXTRACT PHASE COMPRISING ABOUT 20 TO ABOUT 70VOLUME PERCENT OF THE MIXED BASE DISTILLATE FRACTION AND HAVING ASPECIFIC DISPERSION OF AT LEAST ABOUT 160 AND SEPARATING THE FIRSTEXTRACT PHASE INTO A SECOND EXTRACT PHASE AND A SECOND RAFFINATE PHASEFROM WHICH SECOND RAFFINATE PHASE MOST PARAFFINIC AND MOST AROMATICCOMPONENTS HAVE BEEN EXCLUDED BY SAID SOLVENT EXTRACTION TREATMENT ANDSAID SEPARATING AND HAVING A SPECIFIC DISPERSION OF FROM ABOUT 135 TOABOUT 185 AND COMPRISING ABOUT 20 TO ABOUT 70 VOLUME PERCENT OF THEFIRST EXTRACT PHASE, SUBJECTING SAID SECOND RAFFINATE PHASE TO A DEWAXEDTREATMENT, AND HYDROGENATING THE DEWAXED SECOND RAFFINATE PHASE WHILE INCONTACT WITH A HYDROGENATION CATALYST AT A TEMPERATURE FROM ABOUT 600*F.TO ABOUT 750*F., A PRESSURE FROM ABOUT 1000 TO ABOUT 3500 P.S.I.G. ANDAT A WEIGHT HOURLY SPACE VELOCITY FROM ABOUT 0.25 TO ABOUT 3.0 POUNDS OFTHE DEWAXED SECOND RAFFINATE PER POUND OF CATALYST PER HOUR.